Lights in a refrigerator are typically mounted to the interior walls of the refrigerator compartment. While these lights provide sufficient illumination when the refrigerator is empty, when the shelves are filled with goods, light is blocked and portions of the shelves are cast in shadows.
One solution to this problem is placement of lighting systems on the shelves themselves, for example on the underside of the shelves to illuminate the contents of the shelf below or on the upper edges of the shelves to illuminate product on the shelf itself.
A problem with shelf-mounted lighting is getting electrical power to the lights. Refrigerator shelves are typically adjustable in position. While releasable electrical connectors could be provided for connecting electricity to the shelves, these connectors necessarily but undesirably break the continuous inner wall of the refrigerator and expose conductors making cleaning the inner surface of the refrigerator more difficult.
One solution to this problem is described in PCT patent application WO 2009/079209 having a filing date of Dec. 3, 2008 and entitled “Inductively Powered Light Assembly” assigned to the assignee of the present invention and hereby incorporated by reference. The invention described in this application uses inductively coupled power transfer between a primary coil positioned behind the walls of the refrigerator and corresponding coils on the shelves. An elongated primary coil spanning multiple shelf locations may be used to provide flexibility in the arrangement of the shelves.
An improvement in this design is described in pending U.S. application 61/314,833 filed Mar. 17, 2010 and entitled “High-Efficiency Wireless Lighting System” which provides a series of separate, smaller coils that provide more focused electrical coupling between power coils in the walls of the refrigerator and corresponding shelf coils on the shelves. Sensing of coil proximity may be used to efficiently disable coils not being used. This application is also assigned to the assignee of the present invention and hereby incorporated by reference.
It can be difficult to integrate the power coils required for a wireless lighting system into the refrigerator. Mounting the coils behind the refrigerator walls can present manufacturing challenges and the large size of the power transmission coils does not readily integrate into existing shelf brackets.